GNAS and McCune-Albright syndrome: PBMAH is the most common macronodular BAH [previously referred to as massive macronodular adrenocortical disease (MMAD) and ACTH-independent macronodular adrenocortical hyperplasia (AIMAH)] and is largely caused by mutations of the ARMC5 gene (30); several genes have been implicated in other forms of macronodular BAH, including GNAS, APC, and MEN1. Patients with MAS may develop a form of macronodular bilateral adrenal hyperplasia, called primary bimorphic adrenocortical disease (PBAD).